Most exacerbating of chronic obstructive pulmonary disease (COPD) are usually caused by respiratory tract infections. As such, empiric antibiotic therapy can only be considered when the patient displays signs of bacterial infection. According to the GOLD guidelines, antibiotic therapy is only recommended among patients who are critically ill, and displays at least two of the following symptoms including increased dyspnea, increased sputum purulence, and increased sputum production just as displayed in the case of A.M (Li et al., 2019). However, not all patients with the three cardinal symptoms will benefit from antibiotic therapy. As such, it is also necessary to consider the evaluation of biomarkers such as procalcitonin to determine patients who are most likely to benefit from antibiotic therapy.
The most common bacteria that are known to cause acute exacerbation of chronic bronchitis include Streptococcus pneumoniae, Moraxella catarrhalis, andHemophilus influenzae (Ritchie & Wedzicha, 2020). However, for the case of A.M, the most likely causative pathogen is Pseudomonas aeruginosa. The patient’s chest X-ray findings revealed negative results for pneumonia. Consequently, Pseudomonas aeruginosa is considered to be one of the most common nosocomial pathogens which become more prevalent among patients with severe underlying disease. A.M displayed a history of significant COPD with chronic bronchitis, hyperlipidemia, diabetes, and hypertension. Additionally, the sputum gram stain revealed purulent sputum present in the white blood cells, which indicates the presence of a bacterial infection.
Antibiotics recommended by the GOLD guidelines for the management of an acute exacerbation of chronic bronchitis include azithromycin, amoxicillin/clavulanate, or doxycycline. However, in the case of patients who have used antibiotics in the last 30 days, or present with the recurrent disease just like for the case of A.M use of an antibiotic from a different class such as Sulfamethoxazole/trimethoprim (SMX/TMS) is recommended. SMX/TMS is a combination of two active pharmaceutical ingredients with a synergistic effect (Joyner et al., 2020). Sulfamethoxazole is a sulfonamide that acts by inhibiting the synthesis of bacterial dihydrofolic acid as a result of being structurally similar to an endogenous substrate known as para-aminobenzoic acid (PABA). Sulfamethoxazole is a competitive inhibitor of dihydropteroate synthase which is responsible for converting PABA to dihydrofolic acid essential for the synthesis of purines and DNA of the bacteria, hence leading to a bacteriostatic effect (Dietrich et al., 2019). Trimethoprim on the other hand acts by reversibly inhibiting dihydrofolate reductase, which is an essential enzyme responsible for the formation of tetrahydrofolic acid (THF) from dihydrofolic acid (DHF). THF is essential for the synthesis of bacterial nucleic acids and proteins. A combination of the two drugs inhibits two consecutive steps in the synthesis of bacterial nucleic acid and proteins exhibiting a bactericidal effect. The patient must be informed that this medication can lead to increased sensitivity to the sun, hence A.M should limit his time in the sun when using SMX/TMS. Additionally, the drug is known to affect the blood sugar levels of patients with diabetes, like A.M. As such, he should be advised to monitor his blood sugar levels more frequently.
References
Dietrich, E., Klinker, K. P., Li, J., Nguyen, C. T., Quillen, D., & Davis, K. A. (2019). Antibiotic stewardship for acute exacerbation of chronic obstructive pulmonary disease. American Journal of Therapeutics, 26(4), e499-e501. DOI: 10.1097/MJT.0000000000000717
Joyner, K. R., Walkerly, A., Seidel, K., Walsh, N., Damshekan, N., Perry, T., & Soric, M. M. (2020). Comparison of narrow-versus broad-spectrum antibiotics in elderly patients with acute exacerbations of chronic obstructive pulmonary disease. Journal of Pharmacy Practice, 0897190020938190. https://doi.org/10.1177/0897190020938190
Li, Z., Yuan, X., Yu, L., Wang, B., Gao, F., & Ma, J. (2019). Procalcitonin-guided antibiotic therapy in acute exacerbation of chronic obstructive pulmonary disease: an updated meta-analysis. Medicine, 98(32). DOI: 10.1097/MD.0000000000016775
Ritchie, A. I., & Wedzicha, J. A. (2020). Definition, causes, pathogenesis, and consequences of chronic obstructive pulmonary disease exacerbations. Clinics in chest medicine, 41(3), 421-438. https://doi.org/10.1016/j.ccm.2020.06.007